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PHP Forms To Validate Names, Emails And URLs

form_validation.php

<?php
// define variables and set to empty values.

$nameErr = $emailErr = $genderErr = $websiteErr = " ";
$name = $email = $gender = $comment = $website = " ";

  // check if the server method is post.
  if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // name validation.
    if (empty($_POST["name"])) {
      $nameErr = "Name is required";
    } else {
      $name = test_input($_POST["name"]);
      // check if name only contains letters and whitespace.
      if (!preg_match("/^[a-zA-Z-' ]*$/",$name)) {
        $nameErr = "Only letters and white space allowed";
      }
    } 
    // email validation.
    if (empty($_POST["email"])) {
      $emailErr = "Email is required";
    } else {
      $email = test_input($_POST["email"]);
      // check if e-mail address is well-formed.
      if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $emailErr = "Invalid email format";
      }
    }  
    // website validation.
    if (empty($_POST["website"])) {
      $website = "";
    } else {
      $website = test_input($_POST["website"]);
      // check if URL address syntax is valid.
      if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website)) {
        $websiteErr = "Invalid URL";
      }
    }  
    // comment validation.
    if (empty($_POST["comment"])) {
      $comment = "";
    } else {
      $comment = test_input($_POST["comment"]);
    } 
    // gender validation.
    if (empty($_POST["gender"])) {
      $genderErr = "Gender is required";
    } else {
      $gender = test_input($_POST["gender"]);
    }  
  }  
?>